By Brooks Morse // 2020-08-10
These commonly used stormwater collection basins are often confused with one another. Builders in the home development business use the term “retention” for all ponds and basins but never know that most basins in the arid west are actually detention basins. A detention basin is best described as a pond that holds water for a short period of time before it enters a waterway or dissipates. They are often called dry ponds and benefit subdivisions when the land available for construction has an appealing slope. Also, most frequently are used to satisfy city ordinances that require a subdivision to have 20 to 30 percent open areas. Detention ponds double as a park or open grass park because of these ordinances.
Retention ponds or wet ponds are basins that maintain a pool of water throughout the year and hold stormwater runoff. These ponds fluctuate in response to rain events and runoff from adjacent areas. Because retention ponds hold water for a longer period of time than a detention pond, it allows the smaller pollutants like fine sediments to settle to the bottom of the pond before entering another waterway. You will see retention ponds constructed in areas that have a high groundwater table and isn’t feasible for a detention pond.